The present invention relates to motion detection systems and, more particularly, passive infrared motion detectors that have an adjustable field of view to facilitate their mounting in either a corner or on a wall.
Passive infrared (PIR) motion detectors are well known in the art and are used to detect the presence of a human intruder by sensing the thermal energy radiated by the intruder. Generally, such PIR detectors are designed to have a horizontal field of view that has an angular range of between 85 and 90 degrees. Using this range for the field of view allows the detector to be mounted in an interior corner. By utilizing a horizontal field of view that is slightly less than 90 degrees, false alarms caused by objects on the adjacent walls can be reduced.
Oftentimes, it is desirable to mount detectors on planar walls rather than interior corners. Unfortunately, the corner-adapted detectors have a horizontal field of view of only 90 degrees. As a result, when mounted on planar walls, such detectors fail to provide coverage in the areas to the side of the detector. Accordingly, detectors having a 180 degree field of view have been proposed. Although effective for wall mounting, these detectors are not effective in interior corner mount situations. The 180 degree field intersects the walls forming the interior corner and, therefore, detects changes in thermal energy of objects on the walls. Objects on the wall, such as windows, curtains and blinds, often experience a significant change in thermal energy as the sun heats these objects. Such changes in thermal energy can be detected by the 180 degree, corner-mounted detector creating false alarms. Consequently, a need remains for an improved detector that may be effectively used in either corner and wall mounting applications and which includes a means for properly adjusting the field of view of the detector and inhibiting the incorrect installation of the detector.
The present invention provides a detector capable of being mounted on either a planar wall or an interior corner and having an adjustable field of view.
The invention comprises, in one form thereof, an intrusion detection system that includes first and second sensors, each of the first and second sensors having a horizontal field of view of approximately 90 degrees. A housing is also included and the first and second sensors are mounted within the housing wherein a portion of the housing is moveable relative to at least one of the first and second sensors to thereby define first and second relative positions wherein when the housing portion and the first and second sensors are in the first relative position the first and second sensors define a combined horizontal field of view of approximately 180 degrees and wherein when the housing portion and the first and second sensors are in the second relative position the first and second sensors define a combined horizontal field of view of approximately 90 degrees. A biasing member biases the first and second sensors and the housing portion towards one of the first and second relative positions.
The first and second sensors may be fixedly mounted relative to each other with the housing portion defining at least one moveable blinder. Alternatively, the first and second sensors may be relatively moveable and, in the first relative position, the horizontal fields of view of the first and second sensors are substantially overlapping and, in the second relative position, the horizontal fields of view of the first and second sensors are substantially non-overlapping.
The invention comprises, in another form thereof, an intrusion detection system that includes first and second sensors wherein each of the first and second sensors have a horizontal field of view of approximately 90 degrees. A housing is included and the first and second sensors are mounted within the housing wherein a portion of the housing is moveable relative to at least one of the first and second sensors to thereby define first and second relative positions wherein, when the housing portion and the first and second sensors are in the first relative position, the first and second sensors define a combined horizontal field of view of approximately 180 degrees and wherein, when the housing portion and the first and second sensors are in the second relative position, the first and second sensors define a combined horizontal field of view of approximately 90 degrees. A positioning member is also included. Movement of the positioning member positively positions the first and second sensors and the housing portion in a selected relative position to thereby define a selected horizontal field of view. In some embodiments, a biasing element is included which biases the first and second sensors and the housing portion towards one of the first and second relative positions. The first and second sensors and the housing portion may also be positionable between the first and second relative positions to thereby define a horizontal field of view between 90 and 180 degrees.
The invention comprises, in one form thereof, an intrusion detection system including first and second sensors positioned to provide a horizontal field of view defining an angle of approximately 180 degrees. The detection system also includes at least one blinder having a first position wherein the first and second sensors have a horizontal field of view defining an angle of approximately 180 degrees and a second position wherein the first and second sensors have a horizontal field of view defining an angle of approximately 90 degrees. A biasing member biases the blinder toward a first one of the first and second positions. A positioning member having a first member position and a second member position biases the blinder toward the other of the first and second positions when in the first member position while the biasing member biases the blinder into the first one of the first and second position when the positioning member is in the second member position.
The detection system may also include a housing mountable to either an interior corner or a planar wall. The housing has a first set of attachment features used when securing the housing to a planar wall and a second set of attachment features used when securing the housing to an interior corner. The securement of the housing to a planar wall using the first attachment features disposes the positioning member in one of the first member position and the second member position. The securement of the housing to an interior corner using the second attachment features disposes the positioning member in the other of the first member position and the second member position.
In another form, the detection system includes first, second and third sensors. Each of the first and second sensors have a downwardly directed line of sight and are positioned to provide a horizontal field of view defining an angle of approximately 180 degrees. The third sensor has a line of sight oriented substantially horizontally and has a horizontal field of view defining an angle of approximately 90 degrees. At least one blinder is provided and has a first position wherein the third sensor has a substantially unobstructed horizontal field of view while the first and second sensors have a horizontal field of view defining an angle of at least about 180 degrees, and a second position wherein the third sensor has a substantially unobstructed horizontal field of view while the first and second sensors have a horizontal field of view defining an angle of approximately 90 degrees.
The invention comprises, in yet another form thereof, a method of adjusting the detection field of an intrusion detection system. The method includes providing a first sensor and a second sensor, each of the first and second sensors having a horizontal field of view of approximately 90 degrees, the first and second sensors disposed within a housing and wherein the first and second sensors and the housing are relatively positionable to define a first horizontal field of view of approximately 90 degrees and a second horizontal field of view of approximately 180 degrees. The method also includes mounting the housing in one of a first and second location, the first location being in a corner and the second location being on a planar wall and positioning the first and second sensors and housing to define a horizontal field of view of approximately 90 degrees when the housing is mounted the first location and positioning the first and second sensors and housing to define a horizontal field of view of approximately 180 degrees when the housing is mounted in the second location. The method may also include generating an alarm signal when one of the first and second sensors detects an intruder.
An advantage of the present invention is that it provides a single detector that can be mounted in either a corner or on a planar wall wherein the horizontal field of view of the detector is easily adjusted to account for the two different mounting options. Moreover, the present invention also inhibits the installation of the device with the improper horizontal field of view.
Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplification set out herein illustrates embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed.